The subject matter discussed in the background section should not be assumed to be prior art merely as a result of its mention in the background section. Similarly, a problem mentioned in the background section or associated with the subject matter of the background section should not be assumed to have been previously recognized in the prior art. The subject matter in the background section merely represents different approaches, which in and of themselves may also be inventions.
Pattern verification, such as in a context of registration of a trusted fingerprint into a trusted memory of a fingerprint verification system, requires a sufficiently accurate and precise image of the trusted fingerprint (how accurate and how precise are dependent upon design considerations of a particular embodiment). This image may be obtained directly from an imaging sensor. This may be suitable for large area imaging sensors. However, for many applications, the trusted image is reconstituted from image portions of the trusted fingerprint taken from a sensor having a sensing area smaller than the final image. For many mobile applications and electronic platforms, such as smartphones and the like, the use of the small sensor provides a smaller form factor having a lower cost of goods which is important to implementation and adoption. However use of the smaller sensor impacts registration and user experiences during verification.
Any mobile electronic platform having a fingerprint verification system typically includes a registration system that establishes and writes one or more trusted images into a trusted database/memory. Test fingerprints are compared against the trusted image(s) using a matching engine that matches features of interest from the test fingerprint against features of interest from the trusted image(s). A quality of the test image and of the trusted images impact the user experience.
Many systems using a small area sensor therefore register a single finger using multiple impressions. An initial impression of an image portion always provides completely unique information of the larger image to be reconstituted. However, subsequent impressions have varying usefulness depending upon whether the user provides an impression that partially overlaps and partially presents new image data. The user has difficulties in placing a finger for multiple impressions to ensure only unique partial overlapping data is presented with each impression, particularly over a breadth of an entire fingerprint pattern. It is too easy for a user to provide subsequent images with too much overlap or with too little or no overlap. A user does not know when or if they have provided enough sufficiently overlapping image impressions that map enough of the total fingerprint to provide an end product that provides the user with an easy-to-use verification system.
From a perspective of a user, this can become very challenging as the sensor imaging area decreases. Registration systems may not provide feedback to the user of a status of the finger area mapping process. An accuracy of the registration process is degraded when the set of image portions are unable to produce the needed larger image.
Systems for processing image portions of a pattern may sometimes be desirably implemented using limited computing and memory resources. As an active area of a sensor decreases, a greater number of image portions are needed to cover any particular area of the pattern. Managing and processing multiple portions of a pattern can sometimes negatively impact performance, unless other systems and methods are implemented to counter this impact which may add additional complexity and costs.
In addition to these technical details, the initial registration into trusted memory has typically been performed after a device is initialized such as from a new purchase or a complete memory reset which clears trusted information from the trusted memory. At this time, there can be a tension between a user investing enough time to develop a sufficiently robust set of data in the trusted memory and actually using the device. For some users, they may skip this initial investment and never return to this procedure. The amount of time needed for the sufficiently robust set of data is at least partially implicated by use of small area sensors such that a time to develop the set of data may be longer than with a larger area sensor.
Dynamic registration may help address this concern. In a dynamic registration system, there may, or may not, be an initial trusted mode of collecting a limited set of trusted information with the knowledge that this limited set would typically be unsatisfactory over extended use (with security being either too open or too restrictive depending upon implementation). Then this initial trusted mode is followed by a dynamic non-trusted mode during which the user is actively using a fingerprint to unlock/enable the device. Therefore, as the user presents his finger for matching, the device may update the set of trusted information used to match the finger over time. The user need not be aware of this process running in the background of using their device. The dynamic registration mode does not necessarily have an end point and it may continue throughout the life of the device.
Unfortunately, such dynamic systems may expose the device and the user to security vulnerabilities as other people use the device, some of whom may have malicious intent. The dynamic system does not know which information from a fingerprint sensor is provided by the user, or know whether the information comes from the target finger of the user (the user may touch the sensor with different fingers). Such systems may employ various authentication systems to confirm that certain “dynamic information,” that is information developed during dynamic mode, is authorized to be added into trusted memory. Unfortunately, for most users, they may not be sure of how to respond to a query about whether certain dynamic information should be added into trusted memory. They may not know which information was collected, from whom, and when the information was collected.
Further, any dynamic registration system that relies on a password for adding information into trusted memory may subject the fingerprint system to the vulnerabilities associated with passwords. For some users, fingerprint verification is often used to counter some problems with passwords, and having a password associated with the registration of dynamic information into trusted memory may effectively defeat benefits of having a fingerprint system.
What is needed is a system, method, and computer program for efficiently and securely evolving a pattern, such as a fingerprint representation, from a dynamic set of impressions from an impressioner collecting an input responsive to a pattern-under-test.